Abrasive wheel



March 19, 1963 R. A. BULLARD ABRASIVE WHEEL Original Filed Dec. 7, 1959 FIG. I

FIG. 2.

ROBERT A BULLARD IN VEN TOR.

BY W W 4 '4 ATTORNEY United States Patent M 3,081,584 ABRASIVE WHEEL Robert A. Ballard, Westboro, Mass, assignor to George H. Bollard (10., Inc, Westboro, Mass, a corporation of Massachusetts This invention relates to an arbrasive wheel and more particularly to the type of abrasive wheel normally used for removing projections from castings or the like. This application is a continuation of my patent application Serial No. 857,936, filed December 7, 1959, now abancloned.

The particular type of wheel with which the invention is concerned is used for snagging and is generally used for removing rough spots from machine work, weldments, concrete surfaces, and the like. In the past, abrasive wheels that have been used for this purpose in which a flat surface was used for the grinding operation had been generally made in the form of a disk with a central hole which was held on a portable hand grinder and other machines by means of washers or clamps on either side of the disk; these are known in the industry as type 27 wheels. Changing such a wheel requires a considerable [amount of work on the part of the operator. Furthermore, difiiculty has been experienced with losing the washers as well as the large nut which holds the washer and the wheel together. At times the nut becomes loosened and permits the wheel to spin. Furthermore, the shear strength of the center of the Wheel has not been very great and breaking has taken place in these areas. These and other difiiculties experienced with the prior art devices of this kind have been obviated in a novel manner by the present invention.

It is, therefore, an out-sanding object of the invention to provide an abrasive wheel which may be attached to a port-able hand grinder or other machine without the need for clamping washers and a nut.

Another object of this invention is the provision of an abrasive wheel having an integral central hub which is fastened to the wheel in such a manner that the combined hub and wheel are stronger than the wheel itself.

A further object of the present invention is the provision of a snagging wheel which is simple in construction, which is relatively inexpensive to manufacture, and which is capable of a much longer life of useful service than the conventional wheels of this type.

It is another object of the instant invention to provide an abrasive wheel for use with a portable hand grinder or other machine in which the assembly and dis-assembly of the wheel on the grinder is up to 200% faster and which is more useful to the user because purchasing records and stock room records for wheel adapters are eliminated.

With these and other objects in view, :as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a perspective view showing an abrasive wheel embodying the principles of the present invention; and

FIG. 2 is a sectional view of the wheel taken on the line 11-11 of FIG. 1.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the abrasive wheel, indicated generally by the reference numeral 10, is shown as consisting of a disk 11 to which is attached a steel hub 12. The disk is circular and is made up \of a number of layers of fibreglass mesh. The fibreglass is impreg- Patented Mar. 19, 1963 mated with a mixture of an abrasive, such as aluminum oxide or silicon carbide, with a bonding agent which, in the preferred embodiment, is a resinoid organic bond. The bonding agent, when hardened, holds the fibreglass bonding agent and abrasive in a hard inflexible disk, one side of which is provided with grooves 13, as is shown in FIG. 2. The disk is provided with a large central aperture 14 which is provided with a generally conical countersunk portion 15 at the side in which the grooves :13 are formed.

The hub 12 is shown as having a main body 16 with an external surface formed as a hexagon 17. Centrally of the main body 16 is located a threaded aperture 18 provided at the end which is furthest away from the disk and having a cylindrical countersunk portion 19. At the end of the main body 16 opposite the countersunk portion 19 is a tubular projection 21 having a countensunk portion 22 which was originally of generally cylindrical conformation, but because the outer edge of the tubular pro jection has been swaged into the countersunk portion 15 of the disk 11. The countersunk portion 22. has a somewhat conical configuration terminating in a short cylindrical portion. As is evident in FIG. 2, none of the tubular projection 21 extends past the plane of the underside of the disk, this being the side in which the grooves 13 are formed. Although several forms of swaging may be used for accomplishing this purpose, the so-called ball swaging process is preferred, in which a large ball is forced into the countersunk portion 22, thus forging the outer edge of the tubular projection into the countersunk portion 15.

Extending from the main body 16 adjacent the junction of the main body with the tubular projection 14 is a broad circular flange 23 which is relatively thin and extends outwardly of the main body approximately onehalf of the distance from the axis of the disk to its outer periphery. The flange 23 is fastened to the upper surface of the disk 11, which surface faces away from the surface having the grooves 13, by means of a cement 24, which in the preferred embodiment is an epoxy resin usually used with a hardener and which, when completely set, has a tensile shear strength of around 3500 lbs. per square inch. In the preferred embodiment, a sufiicient amount of cement 24 is placed between the flange 23 and the upper surface of the disk 11 so that when the swaging operation takes place the cement is extruded from the outer periphery of the flange 23 and forms a bead 25 in the form of a fillet in the corner of the flange and the disk surface, thus removing the sharp edge that would otherwise be displayed and making the assembled wheel safer to use. Tests have shown that, when the wheel is suitably stressed, failure of the entire wheel takes place in the disk 11 proper rather than any junction between the hub 12 and the disk. This is apparently due to the combination of characteristics provided by a proper cementing between the flange 23 and the upper surface of the disk 11 and the mechanical clamping provided by the swaging of the tubular projection 21 into the countersunk portion 15 of the disk.

It is interesting to note in connection with FIG. 2 that the upper part of the tubular projection 22 has a wall which is much thinner than the main body 16 because of the fact that the under surface of the flange 23 extends inwardly into the hub proper a much greater distance than its upper surface. Furthermore, the thickness of the wall of the projection is even thinner in its lower part because of the countersunk portion 22. The upper part of the projection, therefore, is strong and rigid, but the lower part is thin enough to permit the swaging operation without the necessity for the use of impractical forces in the swaging operation.

It is suspected that, because of the use of fibreglass mesh in bonding the flange 23 to the upper surface of the disk 11, the unexpectedly strong bond that is formed is due in part to the fact that the bond permeates the interstices of the very porous fibreglass mesh disk 11. It isobvious that minor changes may :be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all suchas properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent 1. An abrasive wheel for use with a grinder, comprisihg a disk consisting of a plurality of layers of fiberglass fabric impregnated with a mixture of an abrasive powder and a bonding agent, a metallic hub fastened to the center of the disk and extending from one side only, a threaded aperture in the hub for fastening it to the grinder, an aperture through the disk, a tubular projection on the hub extending through the aperture, the aperture having a countersunk portion at the side opposite the side from which the hub projects, the tubular projection having a wall thickness considerably less than that of the hub in the region of the threaded aperture, the tubular projection being swaged into the countersunk portion so as to be entirely below the surface of the Wheel, the hub having a broad integral flange extending laterally over the said one side of the disk, the flange being cemented to the disk.

2. An abrasive wheel as recited in claim 1, wherein the disk is provided with a flat grinding surface and the integral flange extends radially over the opposite side of the disk.

3. An abrasive wheel as recited in claim 1, wherein the hub is formed with flat surfaces to permit engagement by a wrench.

4. An abrasive wheel for use with a grinder, comprising a disk consisting of a body of fiberglass impregnated with a mixture of anabrasive powder and a bonding agent, a metallic hub fastened to the center of the disk and extending from one side only, a threaded aperture in thehub for fastening it to the grinder, an aperture through the disk, a tubular projection on the hub extending through the aperture, the aperture having a countersunk portion at the side opposite the side from which the hub projects, the tubular projection having a Wall thickness considerably less than that of the hub in the region of the threaded aperture, the tubular projection being swaged into the countersunk portion so as to be entirely below the surface of the wheel, the hub having a broad integral flange extending laterally over the said one side of the disk, the flange being cemented to the disk.

5. An abrasive wheel for usewith a grinder, comprising a disk consisting of a plurality of layers of reinforcing material impregnated with a mixture of an abrasive powder and a bonding agent, a metallic hub fastened to the center of the disk and extending from one side only, a threaded aperture in the hub for fastening it tothe grinder, an aperture through the disk, a tubular projection on the hub extending through the aperture, the aperture having a countersunk portion at the sideopposite the side from whichthe hub projects,.the tubular projection having a wall thickness considerably less than that of the hub in the region of the threaded aperture, the tubular projection being swaged into the countersunk portion so as to be entirely below the surface of the wheel, the hub having a broad integral flange extending laterally over the said one side of the disk, the flange being cemented to the disk. 6. An abrasive wheel for use with a grinder, comprising a disk consisting of a body of reinforcing material impregnated with a mixture of an abrasive powder and a bonding agent, a metallic hub fastened to the center of the disk and extending from one side only, a threaded aperture in the .hub for fastening it to the grinder, an aperture through the disk, a tubular projection on the hub extending through the aperture, the aperture merging into an enlarged recess portion at the side opposite the side from which the hub projects, the tubular projection having a wall thickness considerably less than that of the hub in the region of the threaded aperture, the tubular projection being swaged into the recess portion so as to be entirely below the surface of the Wheel, the hub having abroad integral flange extending laterally over the said one side of the disk, the flange being cemented to the disk.

References Cited in the file of this patent Disclaimer 3,081,584.R0be1't A. B ullard, Vestboro, Mass. ABRASIVE WVHEEL. Patent dated Mar. 19, 1963. Disclaimer filed May 26, 1969, by the assignee, George H. Bullard 00., Inc.

Hereby enters this disclaimer t [Oflical Gazette October 14, 1969.]

0 claims 1, 2, 8, 4, 5 and 6 of said patent. 

1. AN ABRASIVE WHEEL FOR USE WITH A GRINDER, COMPRISING A DISK CONSISTING OF A PLURALITY OF LAYERS OF FIBERGLASS FABRIC IMPREGNATED WITH A MIXTURE OF AN ABRASIVE POWDER AND A BONDING AGENT, A METALLIC HUB FASTENED TO THE CENTER OF THE DISK AND EXTENDING FROM THE SIDE ONLY, A THREADED APERTURE IN THE HUB FOR FASTENING IT TO THE GRINDER, AN APERTURE THROUGH THE DISK, A TUBULAR PROJECTION ON THE HUB EXTENDING THROUGH THE APERTURE, THE APERTURE HAVING A COUNTERSUNK PORTION AT THE SIDE OPPOSITE THE SIDE FROM WHICH THE HUB PROJECTS, THE TUBLUAR PROJECTION HAVING A WALL THICKNESS CONSIDERABLY LESS THAN THAT OF THE HUB IN THE REGION OF THE THREADED APERTURE, THE TUBULAR PROJECTION BEING SWAGED INTO THE COUNTERSUNK PORTION SO AS TO BE ENTIRELY BELOW THE SURFACE OF THE WHEEL, THE HUB HAVING A BOARD INTEGRAL FLANGE EXTENDING LATERALLY OVER THE SAID ONE SIDE OF THE DISK, THE FLANGE BEING CEMENTED TO THE DISK. 